package file.day9_23;

public class Test {
    public static void main(String[] args) {
        int a = 2;
        Sum o1 = new Sum();
        o1.sum(a);//传参，副本而已
        System.out.println(a);//2
    }
}
class Sum{
    public void sum(int a){
        a = a+1;//进行操作不影响原实参的数值
    }
}
